Any alternative British plan has to allow Japan to respond. A major change in British deployments would give Japanese planners reasons to adjust their invasion and air arrangements. Keeping the hypothetical close to the historical situation limits those knock-on effects and makes enemy reactions easier to judge. This narrow setup allows later options for Force Z and Malaya to be tested without assuming that Japan simply waits.
Notable Point · 1:43-2:39
A counterfactual must let Japan react
A radically different British plan would also alter Japan's battle plan, so an alternative must account for enemy adaptation.